The study is the largest of its kind and the first to use a combination of satellite temperature data and long-term ground measurements.

For the study funded by NASA and the National Science Foundation in US, 235 lakes, representing more than half of the world's freshwater supply, were monitored for at least 25 years.

The study found that lakes are warming at an average of 0.34 degrees Celsius each decade. That is greater than the warming rate of either the ocean or the atmosphere and can have profound effects, researchers said.

The temperature of water influences a host of its other properties critical to the health and viability of ecosystems.

When temperature swings quickly and widely from the norm, life forms in a lake can change dramatically and even disappear.

The researchers said various climate factors are associated with the warming trend. In northern climates, lakes are losing their ice cover earlier, and many areas of the world have less cloud cover, exposing their waters more to the sun's warming rays.

The findings were published in the journal Geophysical Research Letters.